Young adult Mexican American women (MA) with low levels of acculturation and literacy have high rates of obesity and experience disproportionate health burdens stemming from weight-related diseases. Although counter-intuitive, obesity has been reliably linked to eating disordered (ED) behaviors, such as binge eating, fasting and self-induced vomiting, and, recent studies show that high BMI, tobacco and alcohol use are strongly associated with bulimia nervosa and binge eating disorders in low literate MA women. Despite evidence linking obesity to ED behaviors, tobacco and alcohol use, few studies have addressed these behaviors in low literate MA women and cutting-edge methodologies to reliably measure risk behaviors have not been extended for use with this at-risk population. The purpose of this study is to develop a cellular phone application to measure ED behaviors, alcohol and tobacco use and their determinants (affect and social context) as they occur in the natural environment and evaluate feasibility and acceptability of this measurement approach in low literate young adult MA women. Four specific aims will be addressed: 1) Develop a cellular phone application to measure ED behaviors, alcohol, tobacco use, mood and social context in low literate young adult MA women, 2) Using the cellular phone application in a pilot study of 58 low literate MA women (18-35 yrs), collect preliminary data on: a) patterns of ED behaviors, alcohol and tobacco use, b) mood and social contexts that precede ED behaviors, and c) validity and reliability of the measurement approach, and 3) Assess adherence and usability of cellular phone to measure ED, alcohol and tobacco use behaviors after 15-day pilot study. A Google Nexus One smartphone will be used as the measurement hardware and a user-centered, iterative design process will be used to develop the application interface. The development process is guided by the bioecological model and consists of 5 phases including: 1) a needs analysis with the research team, 2) development of initial designs and completion of a small user-study (n=8) to evaluate, 3) revision of design and completion of second user evaluation study (n=8) , 4) beta-testing with research team and 5-day testing with MA women (n=3), and, 5) 14-day pilot test of the application with a sample of 58 low acculturated and low literate young adult MA women. This project has the potential to change and improve measurement of health behaviors and health related phenomena in diverse low literate populations who have historically been difficult to study. Furthermore, a user friendly cellular phone device will enable in vivo measurement of socially situated dynamic processes to uncover explanatory mechanisms predicting targeted risk behaviors in highly vulnerable and understudied populations.